Method and apparatus for transferring heat



April 25, 1939. R H, CARR 2,155,383

METHOD AND APPARATUS FOR TRANSFERRING HEAT Filed Dec. 2, 1955 INVENTORRz'cAavdH Carr N- M ATTORNEY Patented Apr. 25, 193

Richard H. Carr, Evanston, 111., Pure Git Company, Chicago, m, a rationof Ohio Application December 2, 1935, No. 52,506

16 Claims.

This invention relates to improvements in method and apparatus for heattransfer, and more particularly to improvements in the construction ofinternal combustion engine pistons and the method of dissipating heatfrom the heads of such pistons.

It is well known that the high temperatures attained in internalcombustion engines cause excess heating of the piston heads withresultant formation and deposition of carbon on the head and pistonrings. Carbon accumulations interfere with the proper operation of theengine, necessitating frequent cleaning with attendant expense and lossof time.

One object of my invention is to provide novel means for transferringheat from one portion to another portion of an enclosed hollow body.

Another object of my invention is to provide a method of rapidlydissipating heat from the head end of a piston, by transferring it tothe skirt and rear end thereof, from which it is absorbed by asurrounding water jacket or carried off by other cooling media such asair.

A further object of my invention is to provide pistons capable ofoperation in an internal combustion engine without becoming excessivelyheated adjacent the head end.

I accomplish the foregoing and other objects of my invention bypartially filling an enclosed hollow piston or other body witha finemetallic or other dust having good heat conductive properties. The dustshould be of such degree of fineness that upon shaking or reciprocatinga body containing a gaseous medium and dust, the latter will remainsuspended as a fog in the gaseous medium for an appreciable length oftime. The rapid reciprocation of a piston in an internal combustionengine produces violent shaking of the dust, thereby causing it tobecome suspended in the gas. Asa result, a continuous heat transferencemedium is produced in the form of the dust laden gas.

As a gaseous suspension medium an inert gas such as carbon monoxide,carbon dioxide, nitrogen, etc., is preferable in order to protect themetallic or other dust from oxidation or deterioration.

The quantity of dust enclosed in the piston will vary with the size ofthe piston, but in any case is insufiicient to completely fill thepiston but is "preferably in excess of the amount necessary to saturatethe gas or remain suspended therein when the piston is reciprocatedduring normal operation of the engine. Thequantity of dust should notfill the internal space of the piston but should be capable of beingfreely shaken about. In order to more clearly comprehend the nature ofmy invention, the following detailed description should be referred toin connection with the accompanying drawing of which as great aspossible.

The single figure is a diagrammatic illustration of one form of pistonembodying my invention.

Referring to the drawing, the numeral i indicates generally a pistonhaving head 3 and shirt 5. The piston shown in the drawing represents aconventional type of piston used in stationary gas engines. A connectingrod i is riveted to the head end of the piston. A plate 9 is welded tothe rear end of the piston. The rod '8 a through a hole in the middle ofthe plate t and a stumng box ll prevents leakage around the connectingrod. The plate has a second opening which is adapted to be closed by ascrew plug it. The hollow interior of the piston is partially filledwith metallic or other finely divided powder it, placed therein byremoving the screw plug l3. The hollow interior of'the piston is alsopreferably filled with an inert gas such as nitrogen or carbon dioxide,although air may be used. The gas may or may not be placed underpressure. The amount of powder placed in the interior of the piston maybe slightly in excess of the amount that the gas can hold in suspensionin order to insure that the density of the dust laden gas is Although alesser amount of dust than that necessary to completely saturate thegas, may be placed in the piston, it is prefer-.

able to have as dense a fog as possible. As metallic dust, steel,aluminum or copper dust of the fineness of that used in the preparationof paints, is suitable.

Although I have described my invention in connection with pistons to beused in connection with stationary gas engines, the invention is alsoapplicable to automotive internal combustion engines which necessitatethe use of a moveable connecting rod. In such cases, instead ofconnecting the rod to the head end of the piston, the rod may beconnected to the skirt of the piston at the rear end thereof by means ofa wrist pin.

Instead of welding the plate 9 to the rear end of the piston, the pistonmay be cast with the rear end plate as an integral part thereof. In suchcases an opening in the rear plate will be provided for removing thecore, used in preparing the casting, and to provide a means for fillingthe interior of the piston with gas and dust.

When the piston is placed in operation, the rapid reciprocation thereofwill cause the dust to become suspended in the gaseous means in themanner illustrated in the drawing. The suspension of the dust creates aheavy dense fog which acts as a continuous conducting medium from 1 thehead to the skirt and rear end of the piston.

thereby rapidly dissipating the heat from the head end to thesurrounding cooling medium which may be either in the form of a waterjacket or other cooling means.

One of the advantages of employing finely divided dust as a conductingmediumis there is no likelihood oi the conducting medium poundingagainst the rear and head end of the cylinder during reciprocation aswould be the case if large particles were contained therein and shakenback and forth. Since the dust is composed of a material that has amelting point in excess of the temperatures attained by the piston, itremains in a solid state during operation. In addition to acting as acontinuous heat transference medium, the dust fog has a tendency toconcentrate at opposite ends of the piston during the backward andforward stroke thereof, thereby providing a more effective means oftaking up the heat from the head end and carrying it to the rear end.

As an illustration of my invention and without intending to be limitedto the specific figures given, a piston weighing four hundred pounds andhaving an internal volume of two thousand six hundred cubic inches, wasfllled'with nitrogen under atmospheric pressure and seven pounds oicopper dust approaching colloidal dimensions were placed therein. Thepiston when operated in a. stationary gas engine proved entirelysatisi'agziry in preventing over-heating of the piston By means 01' myinvention, over-heatingoi the head of the piston can be avoided, and theformation and deposition of carbon and sticking of piston rings to alarge extent eliminated. The

weight of the piston is not materially increased since the amount ofdust is comparatively small in comparison to the weight of the piston.Moreover, improved lubrication of the cylinder and piston is obtained.The reduced carbon formation also permits operation at highercompression ratios.

It will be understood that although I have described my invention inconnection with its use in pistons in internal combustion engines, theinvention in its broad aspect is applicable to transfer of heat in anybody where it is desired to rapidly dissipate heat from a hotter to acooler portion of the body.

What I claim is:

1. The method of transferring heat from one portion to another portionof a closed hollow body which comprises filling the body with a gaseousmedium, partially filling the body with a dust of relative high heatconductivity, said dust being sufliciently fine to remain suspended as afog in said gaseous medium upon shaking said body, closing said body andshaking said body whereby to produce a continuous heat conducting mediumcomprising dust laden gas by means of which heat passes from a hotter toa cooler portion oi said body.

2. The method in accordance with claim 1 in. which the metallic dust isselected from the group consisting of copper, aluminum, iron, and alloysthereof.

3. The method in accordance with claim 1 in which the gaseous medium issubstantially inert toward the dust under the conditions to which thedust is subjected.

4. The method in accordance with claim '1 in.

which the gaseous medium'is selected from the group consisting ofnitrogen, carbon monoxide, carbon dioxide, hydrocarbon gases andmixtures thereon Y 5. The method of distinct* heat from the head end ofaclosed hollcwpiston cl operasuspended in the gas.

tion of an internal combustion engine which comprises filling the hollowspace of the piston with.

a gaseous medium, and partially filling the hollow space with a heatconducting dust of sumcient fineness to remain in suspension as a fog insaid gaseous medium during reciprocation of said piston, closing thepiston and reciprocating the piston at a rate sufllcient to cause thedust to become suspended as a fog in. the gaseous medium.

6. Method according to claim 5 in which the dust remains solid underoperating conditions;

7. Method according to. claim 5 in which the dust is a metallicsubstance which remains solid 10. Means according to claim 9 in whichthe gaseous medium is inert toward the dust and the dust is a metallicsubstance which does not melt at the temperatures to which it issubjected.

11. A piston comprising an enclosed hollow space, said space extendingto the head end of said piston, a heat conductive dust in said space, agaseous medium in said space, said dust being present in insufficientquantities to fill said space and being of sufilcient fineness to becomesuspended as a fog in said gaseous medium during reciprocation of saidpiston.

12. A piston in accordance with claim 11 in; which the dust is ametallic powder which remains solid at temperatures to which said pistonis subjected during operation.

13; A piston in accordance with claim 11 in which the gaseous medium isinert toward the dust at temperatures to which the dust is subiected.

14. A piston comprising a completely enclosed hollow space extending tothe head of said piston, high melting point metallic dust enclosed insaid space, a gaseous medium, inert toward said dust, in said space,said dust being of suflicient fineness to remain suspended as a fog insaid gaseous medium during reciprocation of said piston and beingpresent in insuflicient quantities to fill said space. i

15. The method of transferring heat from a hotter portion to a coolerportion of a closed hollow body containing metallic dust and gas whichcomprises shaking the body containing gas and heat conducting metallicdust, suiliciently violently to cause the dust to become suspended andremain suspended as a fog in the gas.

16. The method of transierring heat from'the head end to the side wallsand rear end of a hollow enclosed piston containing gas andheatconducting metallic dust, which comprises reciprocating the pistonat a speed suiliciently great to cause said metallic dust to become andremain MARI) H. CARR.

